Transfer coefficients such as scattering parameters (S-parameters), open-circuit impedance parameters (Z-parameters), and the like are used for an evaluation of characteristics of a high-frequency electronic circuit (hereinafter referred to as “electronic circuit”) such as a large scale integration (LSI) and a printed board. The S-parameters indicate a relationship between an input and an output of an electronic circuit and are calculated by using an analyzer in which a time domain solver such as a finite difference time domain (FDTD) method is used.
A method of calculating S-parameters by the analyzer will be explained with reference to FIG. 11. FIG. 11 illustrates a conventional method of calculating S-parameters. In an example illustrated in FIG. 11, the analyzer inputs an input wave profile from a port k (k<N) of an electronic circuit which is provided with a plurality of ports (N>1), obtains a wave profile to be output, after a transmission, from each port j (j=1 to N), and calculates S-parameters (Skj) between the port k and each port j.
After calculating S-parameters concerning the port k, the analyzer then inputs the input wave profile to a port which is different from the port k and calculates S-parameters concerning the input port. Supposedly in a case of calculating S-parameters concerning all (N) ports, the operation of changing input ports and calculating S-parameters will be performed N times. Here, a Gaussian pulse is used as the input wave profile, for example. More detailed information is obtained in Japanese Laid-Open Patent Publication No. 2001-13181 and Japanese National Publication of International Patent Application No. 2002-536645.
However, there has been a problem of being incapable of calculating S-parameters efficiently among a plurality of ports.
More specifically, the analyzer sequentially inputs an input wave profile to each port of the electronic circuit provided with a plurality of ports and calculates S-parameters concerning each input port each time in the conventional S-parameter calculation method. As a result, the analyzer requires a lot of time for the calculation of S-parameters, which leads to a failure in an effective calculation of S-parameters among a plurality of ports.
Not only in using S-parameters, the problem described above is similarly true but also in using other transfer coefficients such as short-circuit admittance parameters (Y-parameters) and Z-parameters.